This invention relates to field barriers for sports of the type using a ball and racket such as tennis, to methods of constructing such barriers, and to practice backboard type barriers.
Tennis courts are usually bounded by wire mesh fencing to contain the balls within the courts during play. The fencing is almost invariably formed by upright planar sections of wire mesh streched tightly between upright stanchions anchored in the ground where the court is located out of doors. Though in some cases gaps in the fencing do occur, usually the fence as a whole, together with access gates, completely encloses one or a group of adjacent courts by forming a rectangular barrier.
During the course of play balls are continually hit into the fence from which they usually rebound a short distance. The direction of rebound quite frequently has a vectoral component oriented away from the player who last hit the ball. This is because the angle of ball reflection is equal and opposite to the angle of incidence in accordance with Newton's laws of dynamics. Of course since the barrier is composed of wire mesh, it is not completely flat and thus the angle of incidence is not invariably equal and opposite to the angle of incidence. Nevertheless, generally this is the case. As a result it is seen that a ball will tend to rebound away from the player who last struck it making retrieval by that player more difficult. In addition, since the flight of the ball also will typically pass closely by an opposing player the ball rebound will also usually be away from that player too who is likely to be the one to retrieve it. It therefore is seen that in the majority of incidences tennis court fences of the prior art are constructed to rebound balls away from the players. This in turn makes retrieval more time consuming and, in the case of multiple courts of play bounded by a common fence, often causes the balls in play at one court to interfer with play at an adjacent court.
Windy conditions create an additional problem with present day out of doors tennis court fences. The winds first push the balls into the fence from which they rebound slightly. However, after rebound the wind will again push the ball back into the fence. Since the fence is straight adjacent the court surface the ball soon will begin to roll along the fence until it reaches a downwind corner. With multi-court fences its final resting place may, in some cases, be several courts away from that in which it was in play.
In addition to barriers placed about sports fields other barriers have also been constructed and erected for solo practice. In tennis these are termed backboards and, as opposed to the wire mesh structure of court fences, are constructed of solid materials such as wood or concrete to provide a high degree of rebound for continuous practice. Again here, however, the rebound direction tends to have a vectoral component oriented away from the player in all cases except where the ball is hit normally, i.e. at a 90.degree. angle of incidence, onto the backboard. The further from normal the more aggreviated the condition. In addition, the predictability of return speed and timing is quite great and therefore unnatural. Accordingly, it is to the just described problems associated with sports field barriers to which the present invention is directed.